Structural analysis applications

An account is given of the application of computer codes for the efficient conduct of three-dimensional inelastic analyses to aircraft gas turbine combustor, turbine blade, and turbine stator vane components. The synergetic consequences of the program's activities are illustrated by an evaluation of the computer analyses of thermal barrier coatings and of the Space Shuttle Main Engine's High Pressure Fuel Turbopump turbine blading. This software, in conjunction with state-of-the-art supercomputers, can significantly reduce design-task burdens

STRUCTURAL ANALYSIS DRIVEN SHOULDER ARTHROPLASTY

Shoulder arthroplasty, the most common treatment option for patients diagnosed with end-stage glenohumeral osteoarthritis, is able to provide pain relief and restore some functionality. However, this highly advanced surgical procedure often suffers from a major complication of glenoid prosthesis loosening. The problem is magnified during repeat surgeries mainly due to the minimal quantity of bone in the glenoid vault. The goals of this dissertation were to perform structural analysis of normal and osteoarthritic glenoid, evaluate glenoid design variable effects on restoring long-lasting functionality to damaged shoulders, and create a finite element model (FEM)-based simulation process for computing subject-specific internal glenoid bone remodeling.3D computer models of normal and osteoarthritic scapulae were created using high-resolution volumetric computed tomography images. The computer models were used for glenoid structural analyses. The morphological measurements were comparable to prior studies. The glenoid was found to be approximated by geometric analogs. The osteoarthritic scapula was highly retroverted compared to the normal, and had relatively higher glenoid bone density. Internal glenoid morphology was quantified for the first time. Two and three dimensional stress analysis was used to compare glenoid prosthesis design variables. A custom program assigned location-specific material properties to the bone elements, based on the computed tomography data, making the FEMs similar to the actual scapula. Cemented or uncemeneted polyethylene pegs, compared to metal, gave stresses comparable to intact scapula.Two dimensional FEM based simulation process for normal glenoid bone remodeling was successfully created and validated. The "element" approach better predicted the actual specimen bone density distribution than the "node". Some of the findings agreed with past studies that is, obtaining "checkerboard" pattern in the "element" approach. The various combinations of multiple loads had minimal effect on the predicted bone density distribution.The computer modeling, numerical stress analysis, and the simulated bone remodeling allowed successful glenoid structural analysis. The approach adopted improved our understanding of the glenoid prosthesis and successful shoulder arthroplasty

Computational engine structural analysis

A significant research activity at the NASA Lewis Research Center is the computational simulation of complex multidisciplinary engine structural problems. This simulation is performed using computational engine structural analysis (CESA) which consists of integrated multidisciplinary computer codes in conjunction with computer post-processing for problem-specific application. A variety of the computational simulations of specific cases are described in some detail in this paper. These case studies include: (1) aeroelastic behavior of bladed rotors, (2) high velocity impact of fan blades, (3) blade-loss transient response, (4) rotor/stator/squeeze-film/bearing interaction, (5) blade-fragment/rotor-burst containment, and (6) structural behavior of advanced swept turboprops. These representative case studies are selected to demonstrate the breath of the problems analyzed and the role of the computer including post-processing and graphical display of voluminous output data

The Firefighter Problem: A Structural Analysis

We consider the complexity of the firefighter problem where b>=1 firefighters are available at each time step. This problem is proved NP-complete even on trees of degree at most three and budget one (Finbow et al.,2007) and on trees of bounded degree b+3 for any fixed budget b>=2 (Bazgan et al.,2012). In this paper, we provide further insight into the complexity landscape of the problem by showing that the pathwidth and the maximum degree of the input graph govern its complexity. More precisely, we first prove that the problem is NP-complete even on trees of pathwidth at most three for any fixed budget b>=1. We then show that the problem turns out to be fixed parameter-tractable with respect to the combined parameter "pathwidth" and "maximum degree" of the input graph

Aircraft Conceptual Structural Design Using the AMMIT Structural Analysis Tool

Aircraft conceptual structural design is the process of developing and refining an idea for an aircraft into a feasible structural design. The process typically involves multiple evaluations of a single configuration and can require designers to examine thousands of concepts. Standard approaches to conducting structural analyses in this phase are either based on the use of historical or empirical data or often require significant expertise in structural analysis to perform these rapid assessments. The AMMIT structural analysis tool includes structural line models and handbook methods wrapped in a simple to use interface that can enable rapid, physics-based structural designs without requiring extensive structural expertise. The objectives of the present paper are to introduce AMMIT, describe the methods used in AMMIT, and present the results of the validation effort. Validation of the AMMIT methodology was performed on nine aircraft to determine the accuracy of the methods, highlight features of AMMIT, and guide future development of the methodology. Results of the validation effort indicated that AMMIT provides a prediction of primary structural weight for each aircraft with an acceptable level of error during the preliminary design phase with a minimal expenditure of computational resources

Structural Analysis of a Dragonfly Wing

Dragonfly wings are highly corrugated, which increases the stiffness and strength of the wing significantly, and results in a lightweight structure with good aerodynamic performance. How insect wings carry aerodynamic and inertial loads, and how the resonant frequency of the flapping wings is tuned for carrying these loads, is however not fully understood. To study this we made a three-dimensional scan of a dragonfly (Sympetrum vulgatum) fore- and hindwing with a micro-CT scanner. The scans contain the complete venation pattern including thickness variations throughout both wings. We subsequently approximated the forewing architecture with an efficient three-dimensional beam and shell model. We then determined the wing’s natural vibration modes and the wing deformation resulting from analytical estimates of 8 load cases containing aerodynamic and inertial loads (using the finite element solver Abaqus). Based on our computations we find that the inertial loads are 1.5 to 3 times higher than aerodynamic pressure loads. We further find that wing deformation is smaller during the downstroke than during the upstroke, due to structural asymmetry. The natural vibration mode analysis revealed that the structural natural frequency of a dragonfly wing in vacuum is 154 Hz, which is approximately 4.8 times higher than the natural flapping frequency of dragonflies in hovering flight (32.3 Hz). This insight in the structural properties of dragonfly wings could inspire the design of more effective wings for insect-sized flapping micro air vehicles: The passive shape of aeroelastically tailored wings inspired by dragonflies can in principle be designed more precisely compared to sail like wings —which can make the dragonfly-like wings more aerodynamically effective

On systematic approaches for interpreted information transfer of inspection data from bridge models to structural analysis

In conjunction with the improved methods of monitoring damage and degradation processes, the interest in reliability assessment of reinforced concrete bridges is increasing in recent years. Automated imagebased inspections of the structural surface provide valuable data to extract quantitative information about deteriorations, such as crack patterns. However, the knowledge gain results from processing this information in a structural context, i.e. relating the damage artifacts to building components. This way, transformation to structural analysis is enabled. This approach sets two further requirements: availability of structural bridge information and a standardized storage for interoperability with subsequent analysis tools. Since the involved large datasets are only efficiently processed in an automated manner, the implementation of the complete workflow from damage and building data to structural analysis is targeted in this work. First, domain concepts are derived from the back-end tasks: structural analysis, damage modeling, and life-cycle assessment. The common interoperability format, the Industry Foundation Class (IFC), and processes in these domains are further assessed. The need for usercontrolled interpretation steps is identified and the developed prototype thus allows interaction at subsequent model stages. The latter has the advantage that interpretation steps can be individually separated into either a structural analysis or a damage information model or a combination of both. This approach to damage information processing from the perspective of structural analysis is then validated in different case studies

Fatigue and Structural Analysis of Azimuth Thruster Assembly

Composite is stated as constituent of two or more materials which retain their own physical and chemical property during the time of application, but produce a component which inherent the properties of its constituent materials and makes it better for the real time USAge. There are varieties of processing techniques for fabricating composite parts or structures such as: (1) Resin Transfer Moulding, (2) Pultrusion, (3) Filament Winding, (4) Autoclave Moulding. Among all these technique of exercising composite materials, the filament winding technique is the most appropriate because it avails the user with the ease of USAge, as well as gives wide range of degree of freedom for fabricating or manufacturing objects. In the paper we basically reveal the maximum approach made to study basic theory related to the filament winding technique or method, which provides initial platform for the new learner

HOST structural analysis program overview

Hot-section components of aircraft gas turbine engines are subjected to severe thermal structural loading conditions, especially during the startup and takeoff portions of the engine cycle. The most severe and damaging stresses and strains are those induced by the steep thermal gradients induced during the startup transient. These transient stresses and strains are also the most difficult to predict, in part because the temperature gradients and distributions are not well known or readily predictable and, in part, because the cyclic elastic-viscoplastic behavior of the materials at these extremes of temperature and strain are not well known or readily predictable. A broad spectrum of structures related technology programs is underway to address these deficiencies at the basic as well as the applied level. The three key program elements in the HOST structural analysis program are computations, constitutive modeling, and experiments for each research activity. Also shown are tables summarizing each of the activities